I found my grandmother's diaries after she died and I've been lying to my mother about what's in them for three years

My grandmother passed away three years ago. I was the one who cleaned out her bedroom because my mom couldn't bring herself to do it. In the bottom of the wardrobe, under a stack of blankets, I found eleven notebooks. Diaries, going back to the late 1960s. My mom knew they existed. She asked me, the same day, if I'd found them. I said yes. She asked if I would read them first and tell her whether she should. She said she was afraid of what her mother really thought of her. They had a complicated relationship, a lot of silence, a lot of things never said. I read all eleven over about two months. Most of it is ordinary. Weather, church, what things cost, who was sick. But there's a stretch in the 1970s, when my mom was a small child, where my grandmother writes very plainly that she didn't want to be a mother. That she felt nothing when she held her. That she was counting the years untill the house would be empty. It goes on for almost two notebooks. And then, much later, in her seventies, there are pages and pages about how proud she is of my mom. How she wishes she knew how to say it. How she watched her at my wedding and thought "I got something right without deserving it". I told my mother the diaries were mostly grocery lists and garden notes, and that near the end there were some lovely things about her. I copied out three of the late entries by hand and gave them to her. She keeps them in her nightstand. I didn't tell her about the early ones. I told her the older notebooks had water damage and I couldn't make much out. They're in a box in my attic. I honestly don't know if I did the right thing. I took away her chance to know her mother completly, the bad and the good. But I watched her read those three pages and cry in a way I'd never seen, like something she'd carried for fifty years got put down. I'm not going to tell her. I just needed someone to know the notebooks aren't damaged.